SD card read files with LCD

Using Arduino Programming Questions
#1

Im trying to read text in SD card and display on the LCD but it display 2 weird characters after the text. What is it and why does it show up?

#include <SD.h>
#include <SPI.h>

#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7);

File myFile;
const int CSpin = 10;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(CSpin, OUTPUT);
  SD.begin(CSpin);

  lcd.begin(20,4);
  lcd.setBacklightPin(3, POSITIVE);
  lcd.setBacklight(HIGH);
}

void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(0,0);  
  ReadLine();
  myFile.close();
}

void ReadLine(){
  myFile = SD.open("Sample.txt", FILE_READ);
  myFile.seek(0);
  char cr;
  for(unsigned int i = 0; i < (3 - 1);){
    cr = myFile.read();
    if(cr == '\n')
      {
        i++;
      }
  }

  while(true){
    cr = myFile.read();
    Serial.write(cr);
    lcd.print(cr);
    if(cr == '\n'){
      break;
    }
  }
}

I attached a picture of what it looks like

16492366_1407685395930959_1853342979_o.jpg
16492366_1407685395930959_1853342979_o.jpg1136×639 45.3 KB

#2

I just think you have some non-printable characters there. Maybe a carriage return?

And why do you open the file in a function but close it in loop()?

#3

what can I do to get rid of those characters without using the delete ASCII characters?

It was just a test if the arduino can open and close a file in void loop

#4

Option 1: use an editor (in which you make th file) that can show you all characters. For example Notepad++ can do that.
Option 2: Ignore all chars you can't print. So I would say only print chars between 0x20 and 0x7E (included)

#5

Im sorry im new to these can you please give me a sample code of that?

#6 
#include <SD.h>
#include <SPI.h>

#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7);

File myFile;
const int CSpin = 10;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(CSpin, OUTPUT);
  SD.begin(CSpin);

  lcd.begin(20,4);
  lcd.setBacklightPin(3, POSITIVE);
  lcd.setBacklight(HIGH);
}

void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(0,0); 
  ReadLine();
  myFile.close();
}

void ReadLine(){
  myFile = SD.open("Sample.txt", FILE_READ);
  myFile.seek(0);
  char cr;
  for(unsigned int i = 0; i < (3 - 1);){
    cr = myFile.read();
    if(cr == '\n')
      {
        i++;
      }
  }

  while(true){
    cr = myFile.read();
    Serial.write(cr);
    
    if(cr == '\n'){
      break;
    }
    //here...
    else if(cr >= 0x20 && cr <= 0x7E){
      lcd.print(cr);
    }
    
  }
}
#7